The music on your watch is synced from your paired iPhone. You must use the Watch app on your iPhone to add, delete, manage music on your watch.
Sync albums and playlists to your Apple Watch:
You can add specific albums and playlists to your Apple Watch by syncing them. After you sync, you can play the music on your Apple Watch without your iPhone.
- Set your Apple Watch on its charger and make sure that the device is charging.
- On your iPhone, go to Settings > Bluetooth. Make sure Bluetooth is turned on.
- On your iPhone, open the Apple Watch app, then tap the My Watch tab.
- Tap Music > Plus Icon, Add Music.
Manage Albums / Play lists:
- On your iPhone, open the Apple Watch app, then tap the My Watch tab at the bottom of the screen.
- Scroll to Music and tap it, then tap Edit in the upper-right corner. You'll only see Edit if you have music synced to your watch.
- Under Playlists & Albums, tap Delete(minus sign) next to any music that you want to remove, then tap Delete.
Dave